254 THE FOREST LANDS OF FINLAND. 



flow follows, with increased effect ; by a continuation of 

 the process, a cut is sawn, as it were, in the retaining bank 

 with still increasing effects. And as the process goes on, 

 the sides of the channel, which is being formed, are under- 

 mined and fall, and the material is swept away by the 

 flow. The erosive power of water is weak, but the erosive 

 power of water charged with solid material is great ; and 

 proportioned to this are the effects seen. Water will do 

 little to polish granite, but water and sand will do it ; 

 sweet oil will do little to polish steel, but sweet oil charged 

 with emery, or even with rotten-stone, is all-powerful ; the 

 wind can do little to polish glass or garnet, but sea sand, 

 borne onward by the wind, tells upon the hardest rocks, 

 and will polish both glass and gems. And so is it with 

 the water charged with mud, and sand, and gravel, and 

 stones. The sides of the rocky bed of a rapid are under- 

 mined and fall ; and the swirl of stone-laden water at the 

 foot of a waterfall dashes the force it has obtained against 

 the rock over which it has poured, and undermines and 

 brings down this as well as the confining walls of rock at 

 the sides of the current. At the Falls of Niagara may be 

 seen what may thus be done. Over these Falls pours all 

 the water coming from Lake Superior, Lake Michigan, 

 Lake Huron, and Lake Erie, to Lake Ontaria. The cataract 

 is said to have receded 50 yards since the commencement 

 of the present century. Below the Falls the river flows in 

 a channel which has been thus formed. It extends for 

 miles, is 150 feet deep, and 160 yards, or well nigh 500 

 feet, wide, and the process is still going on. A remarkable 

 occurrence in connection with this, which occurred within 

 the last five-and-twenty years, was the fall of Table Kock. 

 Of this a contributor to the Philadelphia Bulletin wrote : 



' I said I had something to do with the fall of Table 

 Rock, that broad shell on the Canada side, which in 1850 

 looked over the very cauldron of seething waters, but which 

 tumbled in to it on a certain day in the month of June of 

 that, by me, well remembered year. About noon on that 

 day I accompanied a lady from the Clifton House to the 



